What is causing this early yellowing of the bottom leaves?

This has happened to just about all the plants I have tried to grow. There is no ferts, under CFLs, around 88 degrees, PH is 7 going in but 6 coming out so I think this soil may be acidic but then again it is "seed starting" formula so it is should be gentle enough for seedlings. The yellowing progress starts early, like when the second set of true leaves start, the first set starts to lighten up. When the second set is done, and the third set starts the first set is all yellow and the second is starting. So on and so on. Is this normal, because it has happened a lot. Sorry the picture came out like crap, but you get the idea.

do you have drainage holes in those pots.... it looks like over watering to me, you should use nutes and plenty of perlite

Over watering.

I guess I should have mentioned my watering habits.. Yes there are lots of holes. I water every 2-3 days, when the soil is away from the sides of the cup. I highly doubt that it is over watering. When I do water it is just enough to have a drop or two come out of the bottom. All of that white on top is perlite. I think I actually put too much. And even I know using nutes are out of the question, it is not even two weeks old. Any other ideas?

Sometimes in a pot that small one flushes out the nutes in the soil from watering. If ya did not over water i would transplant to fresh soil. Its due for that anyways. If ya dnt transplant then feed them.

You are not using nutes? Pot uses lots of nitrogen during veg and not enough causes yellowing and pale green color. If you are not feeding them that is the problem. Feed them a complete fertilizer like Foxfarms Grow Big and you should notice a change in 4-5 days. 88 degrees is a little too hot. At 85 the stomas start to close and growth slows so try and keep 84 degrees or below! Good Luck!

Cool. Fresh soil it is, maybe a different brand too. How big of a plant do you think I could get out of this size pot? It is actually a 32oz cup, cut a little shorter than normal. It is in a micro cab (PC case), so I don't need them to grow larger than a foot or so. There are 6 of these cups in the PC case that fit very nicely so I would rather not change to a larger pot. I'm kind of going for sea of green but with a slightly longer veg time. Are they going to go root bound before they can reach an optimal height?

And why is everyone saying add nutes? I have been told numerous times not to feed them anything for a month. Last time a fed a plant this old (less than 2 weeks) with a 1/4 strength nute it burned this shit out of it.

They say they dnt add nutes in a large pot of soil because there are plenty of nutes, and if ya keep up on transplanting its always in fresh soil with nutes.

You are going to have to put them in bigger pots to get some pot. Re-think your grow area.

are you speaking of naturally occurring nutes in the soil because there are no time release nutes or anything in my soil.

The natural nutes in the soil.